In Captivate 8 can you resize just the software simulations you've recorded. What I am finding is that if I size it to what I want it to be, I can't reach some of the buttons I need to (they are cut off and the software has no scroll bars). So could I record the demo bigger and then resize it? If so, how?

Do you mean that you have other slides besides the software sim slides? If yes, you'll need to do all the editing to the software sim slides in a separate project including the resizing. However: be careful because changing the resolution (size) is always leading to a quality loss. Or maybe you are looking for a solution like I described in this old blog post: